The goal of this study is to determine how the neurochemical circuitry of cat retina contributes to its function in processing visual information. Specifically, it seeks to determine the neurotransmitter content of morphologically defined neuronal subpopulations; to elucidate the synaptic relationships between chemically specific cells; to determine changes in transmitters levels under various stimulus conditions; and to ascertainthe neurochemical input to define populations of ganglion cell. The findings will be correlated with on-going studies of the morphology, physiology, and pharmacology of these neurons. A knowledge of how chemically specific neurons interact within the retina will contribute not only to the development of models of retinal function but will also assist in the understanding of transmitter function throughotu the nervous system. Combined Golgi and autoradiographic techniques will be employed to visualize cells which accumulate glycine, GABA, and taurine. Quantitation with this technique will be used to investigate the affinity of specific neurons for a putative transmitter under varying physiological conditions. Antisera will be generated against glycine, GABA, taurine, glutamate, and aspartate and used in immunocytochemical studies. Each antiserum will be directed against an amino acid which ahs been conjugated to bovine serum albumin. Fab fragments of the antisera will be prepared and used for electron microscopy. Combined Golgi and immunocytochemical studies will be used to identify chemically specific cells and to determine their relationships with other neurons. Double label studies will be employed to define transmitter co-localizations and to elucidate synaptic relationships between chemically specific cells.